Summary of internationally available experimental Forecasts for current month and next month for the UK and EireUpdated 301117. (Typically updated during Thursday/Friday). Major updates may be noted on Twitter @T2mike

Interpreted from UKMO.
UKMO 301117 - 5th December to 29th December 2017. Indeterminate mix of colder types (with wintery precip especially in the north) and milder westerly types bringing cloud and rain (especially for the S and W). Some drier spells in between. Overall N likely to be colder than normnal and the S near normal but colder/milder at times.
UKMO 271117 - 2nd December to 26th December 2017. Milder in the S to start but colder air then spreading from the north until about mid December when milder weather returns. Unsettled with rain or showers, these wintry at times mainly in the N but elsewhere over some high ground during the colder spell.
UKMO 221117 - 27th November to 21st December 2017. Mixed with some dry spells and also showers/short spells of rain with risk of some snow over hills, also at lower levels in the north. Later in December more genally wet weather spreading from the west. A slightly colder (or at least on the colder side of normal) than average period (increased frost risk) with only a few milder spells possible mainly in the S/W but more generally milder later in December.
UKMO 171117 - 22nd November to 16th December 2017 Changeable with rain and mild temepratures in the S but drier apart from some wintry showers (mainly hills) and colder in the N. Colder and drier weather extending into the S for time earky December before milder changeable types return.
UKMO 071117 - 11th November to 5tt December 2017 Changeable with rain or showers, especially in the N, also some snow for northern high ground but with short drier more settled spells. The settled spells becoming longer and more likely later in this period. Temperature near normal trending below normal. Icreasing risk of frosts.
UKMO 021117 - 7th November to 1st December 2017. North unsettled with rain or showers and hill snow although some drier spells are possible from time to time. South good chance of longer drier spells although not completely dry and late in period turning more generally unsettled. Temperatures near or a little below normal with risk of fog an frost in S during settled spells.

UKMO contingency 271117
TEMP:
December Slightly below normal. Clustering almost equal above and below normal so not definitely colder than average.
PPN:
December Large even spread, reaches outside range of 1981 to 2010 climatology, but slight clustering at below normal.

NOTEs:
1. NORMAL=typically the model normal based on historic runs rather than the measured normal from observation - hence trends rather than numbers are a better guide.
2. CFS2 seasonal anomalies are with respect to the lead dependent model climatology from the hindcast period (1999-2010) without any adjustment - a very warm decade!.
3. UKMET The hindcast period used for model normal is 1996 to 2009. 42-member ensemble seasonal forecast (120KM res over land) combining and bias correcting all forecast members available prior to issue.
4. CFS2 Weekly forecast anomalies are with respect to 1999-2010 hindcast climatology which was a warm period (SST 1982-2010) also mostly a wet period for Uk
compared to longer period stats.
CFS2 Monthly and seasonal hind cast period 1982-2010
5. NMME data, please see the BAMS article (Kirtman et al. 2014). The NMME project and data dissemination is supported by NOAA, NSF, NASA and DOE. with the
help of NCEP, IRI and NCAR personnel in creating, updating and maintaining the NMME archive.